Vertical III-Nitride Transistors for High Blocking Voltage
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Solution Overview
Problem
Conventional silicon-based power transistors are unsuitable for future generations of hybrid vehicles and high-efficiency applications due to their limited critical electric field and high resistance, leading to large and heavy devices operating at low frequencies.
Innovation Solution
Development of vertical semiconductor transistors using III-nitride semiconductor material with a metal gate region and specific dopant concentrations, along with a dielectric or oxide layer, to enhance blocking voltages and reduce on-resistance, allowing for more efficient thermal management and smaller device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicon-based power transistors are used, then manufacturing is well-established and easy, but the critical electric field is limited and resistance is high, leading to large and heavy devices operating at low frequencies
Solution Approach 1:
The patent changes the material parameter from silicon to III-nitride semiconductor, which fundamentally alters the critical electric field capability and resistance characteristics, enabling smaller and lighter device designs while maintaining or improving blocking voltage performance
Solution Approach 2:
The patent transitions from conventional lateral transistor geometry to a vertical structure where the channel extends in the vertical dimension, allowing current to flow through a longer path with higher electric field tolerance, thereby reducing the device footprint and weight
2Ease of manufacture
If conventional silicon-based power transistors are used, then manufacturing is well-established, but the devices are very large and heavy
Solution Approach 1:
The vertical transistor structure extends the channel in the vertical dimension rather than laterally, allowing the same blocking voltage capability to be achieved in a much smaller lateral footprint, thereby reducing overall device volume
Solution Approach 2:
Changing to III-nitride material with higher critical electric field enables the channel to sustain higher fields over shorter distances, reducing the required channel length and overall device volume while maintaining voltage blocking capability
3Reliability
If conventional silicon-based power transistors are used, then the technology is proven, but operating frequency is limited to low frequencies
Solution Approach 1:
The patent changes the semiconductor material parameter to III-nitride, which has higher electron saturation velocity and mobility, enabling faster switching speeds and higher operating frequencies while maintaining reliability through the vertical structure design
4Reliability
If vertical III-nitride semiconductor transistors are developed, then blocking voltages increase and on-resistance decreases, but fabrication challenges and costs increase
Solution Approach 1:
The vertical structure consolidates multiple functions into a compact three-dimensional arrangement, with the gate wrapping around the channel in a cylindrical configuration, which simplifies the overall device architecture despite the complexity of forming the vertical heterostructure
Solution Approach 2:
The gate structure is formed by wrapping metal layers around the semiconductor channel in a nested cylindrical configuration, with multiple gate regions positioned at different heights, creating a compact integrated structure that achieves high performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The vertical III-nitride semiconductor transistors achieve higher effective current densities and improved thermal management, reducing device size and operational limitations, while addressing fabrication challenges and costs.
Implementation Method 1
a dielectric layer between the at least one semiconductor region and the at least one gate region
Implementation Method 2
The at least one semiconductor region includes a III-nitride semiconductor material. The at least one gate region includes a metal
Data Source
AI summary
A vertical semiconductor transistor and a method of forming the same. A vertical semiconductor transistor has at least one semiconductor region, a source, and at least one gate region. The at least one semiconductor region includes a III-nitride semiconductor material. The source is formed over the at least one semiconductor region. The at least one gate region is formed around at least a portion of the at least one semiconductor region.